title: Fetal and neonatal samples of a precursor surfactant protein B inversely related to gestational age.
abstract: BACKGROUND
  Alveolar-capillary membrane leaks can increase the amount of surfactant protein B (SP-B) in the bloodstream. The purpose of this study was to measure the concentration of C-proSP-B, a SP-B precursor that includes C-terminal domains, in various body fluids of newborn infants and determine its dependence on gestational age.
  
  
  METHODS
  C-pro-SPB was measured in amniotic fluid and umbilical cord blood at birth, and in peripheral blood and urine on postnatal day 3 in 137 newborn infants with a median birth weight of 2015 g (range, 550-4475 g) and gestational age of 34 weeks (range, 23-42 weeks).
  
  
  RESULTS
  C-proSP-B levels differed more than 100-fold among samples. The levels (median; interquartile range) were highest in peripheral blood (655.6 ng/mL; 419.0-1467.0 ng/mL) and lowest in urine (3.08 ng/mL; 2.96-3.35 ng/mL). C-proSP-B levels in amniotic fluid (314.9 ng/mL; 192.7-603.6 ng/mL) were approximately half of those in peripheral blood. In cord blood C-proSP-B was slightly lower (589.1 ng/mL; 181.2-1129.0 ng/mL) compared with peripheral blood. C-proSP-B levels significantly increased in all the fluids sampled except urine with decreasing gestational age (p < 0.001).
  
  
  CONCLUSIONS
  This novel assay allows for the quantitative measurement of C-proSP-B in blood and amniotic fluid. The dependence of C-proSP-B on gestational age may hamper its use for the detection of alveolar leaks in preterm newborns.
authors.affiliation: Department of Neonatology, Charité University Medical Center, Berlin, Germany. christoph.czernik@charite.de.
authors.forename: Christoph
authors.initials: C
authors.lastname: Czernik
authors.forename: Gerd
authors.initials: G
authors.lastname: Schmalisch
authors.forename: Christoph
authors.initials: C
authors.lastname: Bührer
authors.forename: Hans
authors.initials: H
authors.lastname: Proquitté
mesh_terms: D000653:Amniotic Fluid / Q000737:chemistry*; D005260:Female; D005312:Fetal Blood / Q000737:chemistry*; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D008163:Luminescent Measurements; D008297:Male; D011498:Protein Precursors / Q000032:analysis / Q000097:blood* / Q000652:urine; D011510:Proteolipids / Q000032:analysis / Q000097:blood* / Q000652:urine; D018709:Statistics, Nonparametric
chemical_list: D011498:Protein Precursors; D011510:Proteolipids; C105511:surfactant protein B propeptide